WHEN I LEFT my comfortable life in New York City in 1987 for the backstreets of Kyoto, Japan, I knew just what I wanted: clarity, simplicity and depth—all the things I’d tasted during two brief visits to the city’s 800-year-old temples and silent teahouses. I never imagined, after 30 years of living in Japan, that I’d find myself somewhere as rustic and empty as a stony Hebridean island in the Seto Inland Sea, a slow, four-hour trip from Kyoto, where an elderly woman is pushing a wheelbarrow down a narrow lane. Her very presence is a sight; the entire island of Inujima houses all of 47 people. Their average age is almost...